Fluid heater and thermostatic control means therefor



P" 18, 1950 H. F. FEUERFILE 2,504,315

FLUID HEATER AND THERMOSTATIC CONTROL MEANS THEREFOR Filed March 11, 1947 5 m Z a 2 v. a M

Patented Apr. 18, 1950 u FLUID HEATER AND THERMOSTATIC CONTROL MEANS THEREFOR Harry F. Feuerflle, J amaica, N. Y. Application March 11, 1947, Serial No. 733,743

'1 Claims. 1

This invention relates to heating systems for homes and other buildings, employing either hot air, steam or hot water methods of heating, and it has for its object to provide a simple and efficient heater of this type which is extremely economical of fuel.

Another object of the invention is to provide a heater of the above type employing any suitable fuel, such as gas, oil or coal, with means for insuring maximum transfer of heat from the combustion gases to the heating fluid, with resulting conservation of fuel.

Still another object is to provide an automatic self-regulating heater of the foregoing type having novel and improved details of construction and features of operation.

Various other objects and advantages will be apparent a the nature of the invention is more fully disclosed.

It is well known that all conventional furnaces used for heating buildings, etc., are very wasteful of fuel. The fact that a large proportion of the hot combustion gases from such furnaces goes up the flue, and is dissipated in the outside atmosphere, is evident from the heated condition of the chimney whenever the furnace is in use.

My invention provides a simple and highly efficient heating system which avoids the foregoing disadvantages of the prior art and utilizes substantially all the heat energy of the fuel to heat the air, water or other fluid medium employed in the system. For convenience, the invention will be described as applied to a hot air heater employing a gas burner, but it will be evident as the description proceeds that it is equally applicable to hot water heat, steam heat, individual room heaters, etc., and that any other type of fuel may also be employed.

In carrying out the invention, the hot combustion gases from the combustion chamber of the furnace are drawn by suction through a circuitous series of radiator pipe coils mounted in a casing through which the air or other heating medium passes on its way to the rooms which it is desired to heat. The said heating medium (air, in the case of the hot air system herein illustrated) extracts substantially all of the heat from the combustion gases before said gases pass into the chimney, and, if for any reason the temperature of the combustion gases passing to the chimney rises above a predetermined maximum, a thermostat operates to reduce the consumption of fuel as hereinafter described.

The combustion chamber of the furnace opens directly to the chimney, but in the normal operation of the system the chimney is by-passed by the-combustion gases which are drawn directly by a suction fan through the circuitous heat-exchange coils described above. However, in starting the system in operation, before the suction fan starts up, the normal chimney draft insures prompt ignition of the fuel, whereupon the resulting generation of heat actuates a stack switch or thermostat in the combustion chamber and thereby operates the suction fan which sucks the heat through the heat-exchange coils before discharging the spent combustion gases to the chimney, as previously described.

Various proposals have been made in the past to conserve heat in a furnace by erecting 'baiiies or tortuous passages for conveying the combustion gases to the chimney, but these have always been inefi'icient because limited by the necessity of maintaining a heated condition in the chimney so as to produce the necessary suction or draft (caused by heat rising in the chimney) to maintain proper combustion, so that very little saving in fuel has been accomplished. My invention, on the other hand, effects a drastic reduction in the consumption of fuel without materially increasing installation or maintenance costs. A particular feature of the invention is that it permits the use of illuminating gas as a fuel, with all its attendant advantages, at a cost no greater, or even less, than other fuels.

Although the novel features which are characteristic of this invention are set forth more in detail in the claims appended hereto, the nature and scope of the invention may be better understood by referring to the following description, taken in connection with the accompanying drawing forming a part thereof, in which a specific embodiment has been set forth for purposes of illustration.

The drawing is a simplified diagrammatic illustration of a gas-burning hot air furnace embodying the invention.

In the following description certain specific terms are used for convenience in referring to the various details of the invention. These terms, however, are to 'be interpreted as broadly as the state of the art will permit.

The drawing shows a hot air heating system comprising an elongated casing l containing an enclosed furnace or combustion chamber 2 which is connected at the top to a chimney 3 opening into the outer atmosphere.

A blower 4 draws air through an inlet duct 5 into the casing I, and this air. after being heated 3 by passing around combustion chamber 2 and heated coils in casing l (hereinafter described) is propelled by blower 4 into the outlet duct 6 which conveys the hot air to the rooms which it is desired to heat.

The combustion chamber 2 contains a gas burner nozzle I to which gas is supplied from a gas pipe 8 containing an electrically operated main valve 9 controlled by a suitable room thermostat l0, an auxiliary valve I2 hereinafter more fully described, and a gas pilot [3 of conventional design.

The upper portion of combustion chamber 2, at a point below the outlet to chimney 3, is connected by duct l4 to one end of an elongated circuitous radiator comprising a plurality of metal pipes I5 which are mounted in parallel relation in casing l and are connected in series by elbows l6 which are removable for cleaning. The pipes l5 have suitable heat radiating fins H. The opposite end of this radiator coil is connected to a suction fan l8 operated by motor l9, and the outlet of said fan is connected by duct 20 to the chimney 3.

The fan motor I9 is controlled by a stack switch or thermostat 2| within combustion chamber 2. A second thermostat 23 is mounted in the casing of fan l8 in the path of the spent combustion gases and controls a torsional rod or Bourdon wire 24 which actuates the auxiliary gas valve l2 to regulate the gas burner in a manner presently to be described. The lower pipe elbows l6 contain small tubes 25 connected to a drain pipe 26 to carry away condensation in the radiator coil.

The operation of the system is as follows: When the room temperature calls for heat, the room thermostat I operates the electric control valve 9, thus turning on the gas which is ignited at the burner nozzle 1 by pilot l3.

The combustion gases are now carried 011 through the chimney 3. However,- as soon as sufficient heat is generated in combustion chamber 2, the thermostat 2| closes the energizing circuit of motor l9 which operates suction fan l8, thus sucking the combustion gases from chamber 2 directly. through duct l4 and radiator pipes 15, past thermostat 23 and out through outlet duct 20 to the chimney 3.

At the same time the blower 4 is operated, for example by a motor in circuit with fan motor l9, thus drawing cool air through duct into the casing I. This air passes around the wall of combustion chamber 2 and the radiator pipes and fins, and the air thus heated is discharged through outlet duct 6 and through various branch ducts (not shown) to the different rooms which are to be heated.

Whenever the air passing thermostat 23 exceeds a predetermined maximum temperature, this thermostat actuates the control rod 24 which operates valve l2 to lower the gas flame. As thermostat 23 cools again, it reverses itself and actuates the control rod 24 in a direction to increase the fiow of gas through valve l2. The foregoing operation continues until sufilcient heat is drawn by blower 4 to the various rooms of the building, at which time the room thermostat It] operates to close the valve 9 and at the same time open the electric circuit controlling blower 4 and suction fan I8.

Since the thermostat 2| operates almost immediately when struck by heat from burner I,

be seen that there is practically no heat loss through chimney 3 or outlet duct 20.

Although a specific embodiment has been shown and described herein for purposes of illustration, it will be evident to those skilled in the art that the invention is capable of various modifications and adaptations within the scope of the appended claims.

The invention claimed is:

l. A heating system comprising a casing having inlet and outlet ducts for the passage of a fluid to be heated, means for circulating a fluid through said casing, a combustion chamber having a chimney, a fuel burner in said chamber, a radiator in said casing in the path of said fluid having an inlet connected to said chamber and an outlet connected to said chimney, means for circulating combustion gases from said chamber through said radiator to said chimney, temperature responsive means in said chamber operated by heat from said burner for actuating said circulating means, and means responsive to the temperature of the gases adjacent the outlet end of said radiator for controlling the operation of said burner.

2. A heating system comprising a casing having inlet and outlet ducts for the passage of a fluid to be heated, means for circulating a fluid through said casing, a combustion chamber having a chimney, a fuel burner in said chamber, a radiator in said casing in the path of said fluid having an inlet connected to said chamber between said burner and said chimney and an outlet connected to said chimney, means for circulating combustion gases from said chamber through said radiator to said chimney, temperature responsive means in said chamber operated by heat from said burner for actuating said circulating means, a thermostat adjacent the outlet of said radiator in the path of the gases circulating therethrough, and means actuated by said thermostat for controlling the operation of said burner.

3. A heating system comprising a casing having inlet and outlet ducts for the passage of a fluid to be heated, means for circulating a fluid through said casing, an enclosed combustion chamber in said casing in the path of said fluid for heating the latter, a fuel burner in said chamber, a chimney directly connected to said chamber, a radiator in said casing in the path of said fluid having an inlet connected to said chamber between said burner and said chimney and an outlet connected to said chimney, means for circulating combustion gases from said chamber through said radiator to said chimney, tem-.

perature responsive means in said chamber operated by heat from said burner for actuating said circulating means, a thermostat adjacent the outlet of said radiator in the path of the gases circulating therethrough, and means actuated by said thermostat for controlling the operation of said burner.

4. A heating system comprising a casing having inlet and outlet ducts for the passage of a fluid to be heated, means for circulating a fluid through said casing, an enclosed combustion chamber in said casing in the path of said fluid for heating the latter, a fuel burner in said chamber, a chimney directly connected to said chamber, a radiator in said casing in the path of said fluid having an inlet connected to said chamber between said burner and said chimney and an outlet connected to said chimney, a suction fan connected to said radiator for drawing combustion gases from said chamber through said radiator to said chimney, a thermostat in said chamber operated by heat from said burner for actuating said fan to draw said gases through said radiator, a second thermostat adjacent the outlet of said radiator in the path of the gases circulating therethrough, and means actuated by said second thermostat for controlling the operation of said burner.

5. A heating system comprising a casing having inlet and outlet ducts for the passage of a fluid to be heated, means for circulating a fluid through said casing, an enclosed combustion chamber in said casing in the path of said fluid for heating the latter, a fuel burner in said chamber, a chimney directly connected to said chamber, an elongated circuitous radiator in said casing in the path of said fluid having an inlet connected to said chamber between said burner and said chimney and an outlet connected to said chimney, a suction fan connected to said radiator for drawing combustion gases from said chamher through said radiator to said chimney, a thermostat in. said chamber operated by heat from said burner for actuating said fan to draw said gases through said radiator, a second thermostat adjacent the outlet of said radiator in the path of the gases circulating therethrough, and a valve actuated by said second thermostat for controlling the operation of said burner.

6. A heating system comprising a casing having inlet and outlet ductsfor the passage of a fluid to be heated, means for circulating a fluid through said casing, an enclosing combustion chamber in said casing in the path of said fluid for heating the latter, a fuel burner in said chamher, a chimney directly connected to said chamber, an elongated circuitous radiator in said casing in the path of said fluid having an inlet connected to said chamber between said burner and said chimney and an outlet connected to said chimney, a suction fan connected to said radiator for drawing combustion gases from said chamber through said radiator to said chimney, a thermostat in said chamber operated by heat from said burner for actuating said fan to draw said gases through said radiator, a second thermostat adjacent the outlet end of said radiator in the path of the gases circulating therethrough, a valve actuated by said second thermostat for controlling the operation of said burner, and means responsive to changes in the temperature of said heated fluid for controlling the operation of said burner, said path of said fluid having an inlet end connectedto said chamber between said burner and said chimney and an outlet end connected to said chimney, a suction fan connected to said radiator for drawing combustion gases from said chamber through said radiator to said chimney, a thermostat in said chamber operated by heat from said burner for actuating said fan to draw said gases through said radiator, a second thermostat adjacent the outlet end of said radiator in the path of the gases circulating therethrough, a valve actuated by said second thermostat for controlling the operation of said burner, and means including a room thermostat responsive to changes in the temperature of said heated fluid for controlling the operation of said burner, said fluid circulating means and said fan.

HARRY F. FEUERFILE.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS 

